A circuit breaker in general comprises an insulating material housing having a front face, a fastening face, two narrow faces and two broad faces. At least one contact site is located within the insulating material housing, said contact site being formed from a fixed contact piece and a contact piece that can move, wherein the contact piece that can move is held on a contact lever that is mounted in such a manner that it can pivot. Moreover, such an installation switching device comprises a magnetic short circuit current trigger or a thermal excess current trigger, or both a magnetic short circuit current trigger as well as a thermal excess current trigger.
The switching knob protrudes beyond the front face of the housing. The switching knob is mounted in the housing near to the front face on a pivoting axis in such a manner that said switching lever can pivot. The switching knob, the magnetic short circuit current trigger and/or the thermal excess current trigger are operatively connected to a switching lock having a latching site. The latching site is formed between a trigger lever and a ratchet lever. The trigger lever can pivot between a latching position and an unlatching position, either under the influence of the switching knob or under the influence of one of the two triggers. The switching lock is also operatively connected to the contact lever. One advantageous embodiment possibility for such a switching lock is disclosed and described in DE 10 2008 006 863 A1.
The switching knob can be manually pivoted into a switched-on position and into a switched-off position. The switched-on position of the switching knob corresponds in the case of unhindered operation to a closed contact site. The switching lock influences the contact lever in such a manner that the contact piece that can move is pushed with the required contact pressure force against the fixed contact piece.
The switched-off position of the switching knob corresponds to an opened contact site.